Diabetes patients need to measure the blood sugar level (glucose level) regularly, and inject insulin based on the blood sugar level to maintain a normal blood sugar level. To maintain a normal blood sugar level, diabetes patients need to measure the blood sugar level frequently, sample a small amount of blood from fingertips of the patients using a blood test apparatus, and measure the blood sugar level using this sampled blood and a blood sensor for examining blood.
FIG. 35 is a cross-sectional view showing an example of a conventional blood sensor (see Patent Document 1, for example). Blood sensor 1 shown in FIG. 35 is configured with: substrate 3; spacer 4 provided on the upper surface of substrate 3; and cover 5 provided on the upper surface of spacer 4. Blood storing part 6 is provided so as to penetrate substrate 3 and spacer 4 and blood storing part 6 opens toward the side that abuts on the skin (downward in the figure). One end of blood supply channel 8 is connected to storing part 6 and the other end is connected to air hole 9. Blood detecting section 2 is formed in blood supply channel 8, and reagent 10 is placed on detecting section 2.
FIG. 36A is a perspective plan view of blood sensor 1 seen from above (from the cover 5 side). In the blood sensor shown in FIG. 36A, working electrode 14b and counter electrode 14c function as detection electrodes and form detecting section 2. Further, the blood sensor shown in FIG. 36B is also known (see Patent Document 2). Also in the blood sensor shown in FIG. 36B, working electrode 14b and counter electrode 14c function as detection electrodes and form detecting section 2.
The way to use blood sensor 1 will be described using FIG. 37. FIG. 37 shows a state where needle 11 is pulled up and stays in its original position after blood sampling is finished. First, sensor 1 is brought into contact with skin 7 of the patient. Next, puncturing needle 11 is propelled in the direction of arrow 12, Puncturing needle 11 breaks through cover 5 forming upper side 6a of storing part 6, forms puncturing hole 14 in upper side 6a, and, further, penetrates puncturing hole 14 and scars skin 7. Blood 13 flows out from skin 7 where a scar is made. The out flowing blood 13 fills storing part 6. Blood 13 that fills storing part 6 is led to detecting section 2 through supply channel 8 by capillary action.
Then, blood 13 between working electrode 14b and counter electrode 14c reacts with reagent 10 and produces a current proportional to the blood sugar level. The current produced is led to a measuring circuit in the blood test apparatus via a connector that contacts with connection terminal 15b and a connector that contacts with connection terminal 15c. The measuring circuit measures the current proportional to the blood sugar level and calculates the blood sugar level. The calculated blood sugar level provides basic data and the like showing the amount of insulin to administer to the patient.
To measure the blood sugar level using blood sensor 1 in this way, signals from detection electrode 14b and detection electrode 14c have to be transmitted to the measuring circuit in the blood test apparatus reliably via the connectors.    Patent Document 1: Japanese Patent Application Laid-Open No, 2005-110712    Patent Document 2: Japanese Patent Application Laid-Open No. 2000-000231